In a standard aircraft having a pilot and co-pilot, there are typically four brake pedals. Each of the pilot and co-pilot has two brake pedals. For the pilot, the left brake pedal controls the brakes on the left side of the aircraft, and the right brake pedal controls the brakes on the right side of the aircraft. The left and right brake pedals are configured similarly for the co-pilot.
Conventionally, brake pedal deflection (i.e., the magnitude the pedal is deflected relative to its starting, or “at rest” position) corresponds to the braking force applied at the aircraft brake. Typically, the greater the pedal deflection, the greater the amount of force applied by the aircraft brake(s).
In more modern aircraft, brake pedal deflection corresponds to a desired amount of aircraft deceleration, hereinafter referred to as “deceleration command braking.” In these systems, the greater the pedal deflection, the greater the amount of deceleration is desired for the aircraft (also referred to as “desired deceleration”). Such systems measure aircraft deceleration and brake deflection and then calculate the desired deceleration amount. Then, the braking system commands an amount of force at the aircraft brake(s) to achieve the desired level of deceleration. These modern systems allow for more accurate and granular pilot control, thus enhancing safety, braking control, and improving braking maneuvers (e.g., landing and rejected take-offs (“RTO”)).
However, in conventional deceleration command braking, the braking system uses a static mapping of pedal deflection to target deceleration. This is problematic in several ways. For example, during landing, the aircraft is likely already decelerating due to a variety of factors, such as reverse engine thrust, air resistance, and wing flap position. Such other factors cause deceleration unrelated to the force applied at the aircraft brake, which may contribute to “ambient deceleration,” which as used herein refers to the deceleration of an aircraft at a given time. Accordingly, in such conventional systems where aircraft deceleration is already present due to one or more of these factors, as pedal deflection begins, the braking system commands no braking force (i.e., a braking force of 0). It is only when pedal deflection exceeds the ambient deceleration that the braking system will command the application of force at the aircraft brake. In such a scenario, it is feasible that a pilot may deflect the pedal up to 40% prior to activating the aircraft brake.
Accordingly, there is a need for alternate methods and systems for aircraft braking in a deceleration command braking configuration.